<?php
namespace Think\Upload\Driver\Bcs;

/**
 * Handles all HTTP requests using cURL and manages the responses.
 *
 * @version 2011.03.01
 * @copyright 2006-2011 Ryan Parman
 * @copyright 2006-2010 Foleeo Inc.
 * @copyright 2010-2011 Amazon.com, Inc. or its affiliates.
 * @copyright 2008-2011 Contributors
 * @license http://opensource.org/licenses/bsd-license.php Simplified BSD License
 */
class BCS_RequestCore {
    /**
     * The URL being requested.
     */
    public $request_url;
    /**
     * The headers being sent in the request.
     */
    public $request_headers;
    /**
     * The body being sent in the request.
     */
    public $request_body;
    /**
     * The response returned by the request.
     */
    public $response;
    /**
     * The headers returned by the request.
     */
    public $response_headers;
    /**
     * The body returned by the request.
     */
    public $response_body;
    /**
     * The HTTP status code returned by the request.
     */
    public $response_code;
    /**
     * Additional response data.
     */
    public $response_info;
    /**
     * The handle for the cURL object.
     */
    public $curl_handle;
    /**
     * The method by which the request is being made.
     */
    public $method;
    /**
     * Stores the proxy settings to use for the request.
     */
    public $proxy = null;
    /**
     * The username to use for the request.
     */
    public $username = null;
    /**
     * The password to use for the request.
     */
    public $password = null;
    /**
     * Custom CURLOPT settings.
     */
    public $curlopts = null;
    /**
     * The state of debug mode.
     */
    public $debug_mode = false;
    /**
     * The default class to use for HTTP Requests (defaults to <BCS_RequestCore>).
     */
    public $request_class = 'BCS_RequestCore';
    /**
     * The default class to use for HTTP Responses (defaults to <BCS_ResponseCore>).
     */
    public $response_class = 'BCS_ResponseCore';
    /**
     * Default useragent string to use.
     */
    public $useragent = 'BCS_RequestCore/1.4.2';
    /**
     * File to read from while streaming up.
     */
    public $read_file = null;
    /**
     * The resource to read from while streaming up.
     */
    public $read_stream = null;
    /**
     * The size of the stream to read from.
     */
    public $read_stream_size = null;
    /**
     * The length already read from the stream.
     */
    public $read_stream_read = 0;
    /**
     * File to write to while streaming down.
     */
    public $write_file = null;
    /**
     * The resource to write to while streaming down.
     */
    public $write_stream = null;
    /**
     * Stores the intended starting seek position.
     */
    public $seek_position = null;
    /**
     * The user-defined callback function to call when a stream is read from.
     */
    public $registered_streaming_read_callback = null;
    /**
     * The user-defined callback function to call when a stream is written to.
     */
    public $registered_streaming_write_callback = null;
    /*%******************************************************************************************%*/
    // CONSTANTS
    /**
     * GET HTTP Method
     */
    const HTTP_GET = 'GET';
    /**
     * POST HTTP Method
     */
    const HTTP_POST = 'POST';
    /**
     * PUT HTTP Method
     */
    const HTTP_PUT = 'PUT';
    /**
     * DELETE HTTP Method
     */
    const HTTP_DELETE = 'DELETE';
    /**
     * HEAD HTTP Method
     */
    const HTTP_HEAD = 'HEAD';

    /*%******************************************************************************************%*/
    // CONSTRUCTOR/DESTRUCTOR
    /**
     * Constructs a new instance of this class.
     *
     * @param string $url (Optional) The URL to request or service endpoint to query.
     * @param string $proxy (Optional) The faux-url to use for proxy settings. Takes the following format: `proxy://user:pass@hostname:port`
     * @param array $helpers (Optional) An associative array of classnames to use for request, and response functionality. Gets passed in automatically by the calling class.
     * @return $this A reference to the current instance.
     */
    public function __construct($url = null, $proxy = null, $helpers = null) {
        // Set some default values.
        $this->request_url = $url;
        $this->method = self::HTTP_GET;
        $this->request_headers = array ();
        $this->request_body = '';
        // Set a new Request class if one was set.
        if (isset ( $helpers ['request'] ) && ! empty ( $helpers ['request'] )) {
            $this->request_class = $helpers ['request'];
        }
        // Set a new Request class if one was set.
        if (isset ( $helpers ['response'] ) && ! empty ( $helpers ['response'] )) {
            $this->response_class = $helpers ['response'];
        }
        if ($proxy) {
            $this->set_proxy ( $proxy );
        }
        return $this;
    }

    /**
     * Destructs the instance. Closes opened file handles.
     *
     * @return $this A reference to the current instance.
     */
    public function __destruct() {
        if (isset ( $this->read_file ) && isset ( $this->read_stream )) {
            fclose ( $this->read_stream );
        }
        if (isset ( $this->write_file ) && isset ( $this->write_stream )) {
            fclose ( $this->write_stream );
        }
        return $this;
    }

    /*%******************************************************************************************%*/
    // REQUEST METHODS
    /**
     * Sets the credentials to use for authentication.
     *
     * @param string $user (Required) The username to authenticate with.
     * @param string $pass (Required) The password to authenticate with.
     * @return $this A reference to the current instance.
     */
    public function set_credentials($user, $pass) {
        $this->username = $user;
        $this->password = $pass;
        return $this;
    }

    /**
     * Adds a custom HTTP header to the cURL request.
     *
     * @param string $key (Required) The custom HTTP header to set.
     * @param mixed $value (Required) The value to assign to the custom HTTP header.
     * @return $this A reference to the current instance.
     */
    public function add_header($key, $value) {
        $this->request_headers [$key] = $value;
        return $this;
    }

    /**
     * Removes an HTTP header from the cURL request.
     *
     * @param string $key (Required) The custom HTTP header to set.
     * @return $this A reference to the current instance.
     */
    public function remove_header($key) {
        if (isset ( $this->request_headers [$key] )) {
            unset ( $this->request_headers [$key] );
        }
        return $this;
    }

    /**
     * Set the method type for the request.
     *
     * @param string $method (Required) One of the following constants: <HTTP_GET>, <HTTP_POST>, <HTTP_PUT>, <HTTP_HEAD>, <HTTP_DELETE>.
     * @return $this A reference to the current instance.
     */
    public function set_method($method) {
        $this->method = strtoupper ( $method );
        return $this;
    }

    /**
     * Sets a custom useragent string for the class.
     *
     * @param string $ua (Required) The useragent string to use.
     * @return $this A reference to the current instance.
     */
    public function set_useragent($ua) {
        $this->useragent = $ua;
        return $this;
    }

    /**
     * Set the body to send in the request.
     *
     * @param string $body (Required) The textual content to send along in the body of the request.
     * @return $this A reference to the current instance.
     */
    public function set_body($body) {
        $this->request_body = $body;
        return $this;
    }

    /**
     * Set the URL to make the request to.
     *
     * @param string $url (Required) The URL to make the request to.
     * @return $this A reference to the current instance.
     */
    public function set_request_url($url) {
        $this->request_url = $url;
        return $this;
    }

    /**
     * Set additional CURLOPT settings. These will merge with the default settings, and override if
     * there is a duplicate.
     *
     * @param array $curlopts (Optional) A set of key-value pairs that set `CURLOPT` options. These will merge with the existing CURLOPTs, and ones passed here will override the defaults. Keys should be the `CURLOPT_*` constants, not strings.
     * @return $this A reference to the current instance.
     */
    public function set_curlopts($curlopts) {
        $this->curlopts = $curlopts;
        return $this;
    }

    /**
     * Sets the length in bytes to read from the stream while streaming up.
     *
     * @param integer $size (Required) The length in bytes to read from the stream.
     * @return $this A reference to the current instance.
     */
    public function set_read_stream_size($size) {
        $this->read_stream_size = $size;
        return $this;
    }

    /**
     * Sets the resource to read from while streaming up. Reads the stream from its current position until
     * EOF or `$size` bytes have been read. If `$size` is not given it will be determined by <php:fstat()> and
     * <php:ftell()>.
     *
     * @param resource $resource (Required) The readable resource to read from.
     * @param integer $size (Optional) The size of the stream to read.
     * @return $this A reference to the current instance.
     */
    public function set_read_stream($resource, $size = null) {
        if (! isset ( $size ) || $size < 0) {
            $stats = fstat ( $resource );
            if ($stats && $stats ['size'] >= 0) {
                $position = ftell ( $resource );
                if ($position !== false && $position >= 0) {
                    $size = $stats ['size'] - $position;
                }
            }
        }
        $this->read_stream = $resource;
        return $this->set_read_stream_size ( $size );
    }

    /**
     * Sets the file to read from while streaming up.
     *
     * @param string $location (Required) The readable location to read from.
     * @return $this A reference to the current instance.
     */
    public function set_read_file($location) {
        $this->read_file = $location;
        $read_file_handle = fopen ( $location, 'r' );
        return $this->set_read_stream ( $read_file_handle );
    }

    /**
     * Sets the resource to write to while streaming down.
     *
     * @param resource $resource (Required) The writeable resource to write to.
     * @return $this A reference to the current instance.
     */
    public function set_write_stream($resource) {
        $this->write_stream = $resource;
        return $this;
    }

    /**
     * Sets the file to write to while streaming down.
     *
     * @param string $location (Required) The writeable location to write to.
     * @return $this A reference to the current instance.
     */
    public function set_write_file($location) {
        $this->write_file = $location;
        $write_file_handle = fopen ( $location, 'w' );
        return $this->set_write_stream ( $write_file_handle );
    }

    /**
     * Set the proxy to use for making requests.
     *
     * @param string $proxy (Required) The faux-url to use for proxy settings. Takes the following format: `proxy://user:pass@hostname:port`
     * @return $this A reference to the current instance.
     */
    public function set_proxy($proxy) {
        $proxy = parse_url ( $proxy );
        $proxy ['user'] = isset ( $proxy ['user'] ) ? $proxy ['user'] : null;
        $proxy ['pass'] = isset ( $proxy ['pass'] ) ? $proxy ['pass'] : null;
        $proxy ['port'] = isset ( $proxy ['port'] ) ? $proxy ['port'] : null;
        $this->proxy = $proxy;
        return $this;
    }

    /**
     * Set the intended starting seek position.
     *
     * @param integer $position (Required) The byte-position of the stream to begin reading from.
     * @return $this A reference to the current instance.
     */
    public function set_seek_position($position) {
        $this->seek_position = isset ( $position ) ? ( integer ) $position : null;
        return $this;
    }

    /**
     * Register a callback function to execute whenever a data stream is read from using
     * <CFRequest::streaming_read_callback()>.
     *
     * The user-defined callback function should accept three arguments:
     *
     * <ul>
     * <li><code>$curl_handle</code> - <code>resource</code> - Required - The cURL handle resource that represents the in-progress transfer.</li>
     * <li><code>$file_handle</code> - <code>resource</code> - Required - The file handle resource that represents the file on the local file system.</li>
     * <li><code>$length</code> - <code>integer</code> - Required - The length in kilobytes of the data chunk that was transferred.</li>
     * </ul>
     *
     * @param string|array|function $callback (Required) The callback function is called by <php:call_user_func()>, so you can pass the following values: <ul>
     * <li>The name of a global function to execute, passed as a string.</li>
     * <li>A method to execute, passed as <code>array('ClassName', 'MethodName')</code>.</li>
     * <li>An anonymous function (PHP 5.3+).</li></ul>
     * @return $this A reference to the current instance.
     */
    public function register_streaming_read_callback($callback) {
        $this->registered_streaming_read_callback = $callback;
        return $this;
    }

    /**
     * Register a callback function to execute whenever a data stream is written to using
     * <CFRequest::streaming_write_callback()>.
     *
     * The user-defined callback function should accept two arguments:
     *
     * <ul>
     * <li><code>$curl_handle</code> - <code>resource</code> - Required - The cURL handle resource that represents the in-progress transfer.</li>
     * <li><code>$length</code> - <code>integer</code> - Required - The length in kilobytes of the data chunk that was transferred.</li>
     * </ul>
     *
     * @param string|array|function $callback (Required) The callback function is called by <php:call_user_func()>, so you can pass the following values: <ul>
     * <li>The name of a global function to execute, passed as a string.</li>
     * <li>A method to execute, passed as <code>array('ClassName', 'MethodName')</code>.</li>
     * <li>An anonymous function (PHP 5.3+).</li></ul>
     * @return $this A reference to the current instance.
     */
    public function register_streaming_write_callback($callback) {
        $this->registered_streaming_write_callback = $callback;
        return $this;
    }

    /*%******************************************************************************************%*/
    // PREPARE, SEND, AND PROCESS REQUEST
    /**
     * A callback function that is invoked by cURL for streaming up.
     *
     * @param resource $curl_handle (Required) The cURL handle for the request.
     * @param resource $file_handle (Required) The open file handle resource.
     * @param integer $length (Required) The maximum number of bytes to read.
     * @return binary Binary data from a stream.
     */
    public function streaming_read_callback($curl_handle, $file_handle, $length) {
        // Once we've sent as much as we're supposed to send...
        if ($this->read_stream_read >= $this->read_stream_size) {
            // Send EOF
            return '';
        }
        // If we're at the beginning of an upload and need to seek...
        if ($this->read_stream_read == 0 && isset ( $this->seek_position ) && $this->seek_position !== ftell ( $this->read_stream )) {
            if (fseek ( $this->read_stream, $this->seek_position ) !== 0) {
                throw new BCS_RequestCore_Exception ( 'The stream does not support seeking and is either not at the requested position or the position is unknown.' );
            }
        }
        $read = fread ( $this->read_stream, min ( $this->read_stream_size - $this->read_stream_read, $length ) ); // Remaining upload data or cURL's requested chunk size
        $this->read_stream_read += strlen ( $read );
        $out = $read === false ? '' : $read;
        // Execute callback function
        if ($this->registered_streaming_read_callback) {
            call_user_func ( $this->registered_streaming_read_callback, $curl_handle, $file_handle, $out );
        }
        return $out;
    }

    /**
     * A callback function that is invoked by cURL for streaming down.
     *
     * @param resource $curl_handle (Required) The cURL handle for the request.
     * @param binary $data (Required) The data to write.
     * @return integer The number of bytes written.
     */
    public function streaming_write_callback($curl_handle, $data) {
        $length = strlen ( $data );
        $written_total = 0;
        $written_last = 0;
        while ( $written_total < $length ) {
            $written_last = fwrite ( $this->write_stream, substr ( $data, $written_total ) );
            if ($written_last === false) {
                return $written_total;
            }
            $written_total += $written_last;
        }
        // Execute callback function
        if ($this->registered_streaming_write_callback) {
            call_user_func ( $this->registered_streaming_write_callback, $curl_handle, $written_total );
        }
        return $written_total;
    }

    /**
     * Prepares and adds the details of the cURL request. This can be passed along to a <php:curl_multi_exec()>
     * function.
     *
     * @return resource The handle for the cURL object.
     */
    public function prep_request() {
        $curl_handle = curl_init ();
        // Set default options.
        curl_setopt ( $curl_handle, CURLOPT_URL, $this->request_url );
        curl_setopt ( $curl_handle, CURLOPT_FILETIME, true );
        curl_setopt ( $curl_handle, CURLOPT_FRESH_CONNECT, false );
        curl_setopt ( $curl_handle, CURLOPT_SSL_VERIFYPEER, false );
        curl_setopt ( $curl_handle, CURLOPT_SSL_VERIFYHOST, true );
        curl_setopt ( $curl_handle, CURLOPT_CLOSEPOLICY, CURLCLOSEPOLICY_LEAST_RECENTLY_USED );
        curl_setopt ( $curl_handle, CURLOPT_MAXREDIRS, 5 );
        curl_setopt ( $curl_handle, CURLOPT_HEADER, true );
        curl_setopt ( $curl_handle, CURLOPT_RETURNTRANSFER, true );
        curl_setopt ( $curl_handle, CURLOPT_TIMEOUT, 5184000 );
        curl_setopt ( $curl_handle, CURLOPT_CONNECTTIMEOUT, 120 );
        curl_setopt ( $curl_handle, CURLOPT_NOSIGNAL, true );
        curl_setopt ( $curl_handle, CURLOPT_REFERER, $this->request_url );
        curl_setopt ( $curl_handle, CURLOPT_USERAGENT, $this->useragent );
        curl_setopt ( $curl_handle, CURLOPT_READFUNCTION, array (
                $this,
                'streaming_read_callback' ) );
        if ($this->debug_mode) {
            curl_setopt ( $curl_handle, CURLOPT_VERBOSE, true );
        }
        //if (! ini_get ( 'safe_mode' )) {
        //modify by zhengkan
        //curl_setopt($curl_handle, CURLOPT_FOLLOWLOCATION, true);
        //}
        // Enable a proxy connection if requested.
        if ($this->proxy) {
            curl_setopt ( $curl_handle, CURLOPT_HTTPPROXYTUNNEL, true );
            $host = $this->proxy ['host'];
            $host .= ($this->proxy ['port']) ? ':' . $this->proxy ['port'] : '';
            curl_setopt ( $curl_handle, CURLOPT_PROXY, $host );
            if (isset ( $this->proxy ['user'] ) && isset ( $this->proxy ['pass'] )) {
                curl_setopt ( $curl_handle, CURLOPT_PROXYUSERPWD, $this->proxy ['user'] . ':' . $this->proxy ['pass'] );
            }
        }
        // Set credentials for HTTP Basic/Digest Authentication.
        if ($this->username && $this->password) {
            curl_setopt ( $curl_handle, CURLOPT_HTTPAUTH, CURLAUTH_ANY );
            curl_setopt ( $curl_handle, CURLOPT_USERPWD, $this->username . ':' . $this->password );
        }
        // Handle the encoding if we can.
        if (extension_loaded ( 'zlib' )) {
            curl_setopt ( $curl_handle, CURLOPT_ENCODING, '' );
        }
        // Process custom headers
        if (isset ( $this->request_headers ) && count ( $this->request_headers )) {
            $temp_headers = array ();
            foreach ( $this->request_headers as $k => $v ) {
                $temp_headers [] = $k . ': ' . $v;
            }
            curl_setopt ( $curl_handle, CURLOPT_HTTPHEADER, $temp_headers );
        }
        switch ($this->method) {
            case self::HTTP_PUT :
                curl_setopt ( $curl_handle, CURLOPT_CUSTOMREQUEST, 'PUT' );
                if (isset ( $this->read_stream )) {
                    if (! isset ( $this->read_stream_size ) || $this->read_stream_size < 0) {
                        throw new BCS_RequestCore_Exception ( 'The stream size for the streaming upload cannot be determined.' );
                    }
                    curl_setopt ( $curl_handle, CURLOPT_INFILESIZE, $this->read_stream_size );
                    curl_setopt ( $curl_handle, CURLOPT_UPLOAD, true );
                } else {
                    curl_setopt ( $curl_handle, CURLOPT_POSTFIELDS, $this->request_body );
                }
                break;
            case self::HTTP_POST :
                curl_setopt ( $curl_handle, CURLOPT_POST, true );
                curl_setopt ( $curl_handle, CURLOPT_POSTFIELDS, $this->request_body );
                break;
            case self::HTTP_HEAD :
                curl_setopt ( $curl_handle, CURLOPT_CUSTOMREQUEST, self::HTTP_HEAD );
                curl_setopt ( $curl_handle, CURLOPT_NOBODY, 1 );
                break;
            default : // Assumed GET
                curl_setopt ( $curl_handle, CURLOPT_CUSTOMREQUEST, $this->method );
                if (isset ( $this->write_stream )) {
                    curl_setopt ( $curl_handle, CURLOPT_WRITEFUNCTION, array (
                            $this,
                            'streaming_write_callback' ) );
                    curl_setopt ( $curl_handle, CURLOPT_HEADER, false );
                } else {
                    curl_setopt ( $curl_handle, CURLOPT_POSTFIELDS, $this->request_body );
                }
                break;
        }
        // Merge in the CURLOPTs
        if (isset ( $this->curlopts ) && sizeof ( $this->curlopts ) > 0) {
            foreach ( $this->curlopts as $k => $v ) {
                curl_setopt ( $curl_handle, $k, $v );
            }
        }
        return $curl_handle;
    }

    /**
     * is the environment BAE?
     * @return boolean the result of the answer
     */
    private function isBaeEnv() {
        if (isset ( $_SERVER ['HTTP_HOST'] )) {
            $host = $_SERVER ['HTTP_HOST'];
            $pos = strpos ( $host, '.' );
            if ($pos !== false) {
                $substr = substr ( $host, $pos + 1 );
                if ($substr == 'duapp.com') {
                    return true;
                }
            }
        }
        if (isset ( $_SERVER ["HTTP_BAE_LOGID"] )) {
            return true;
        }

        return false;
    }

    /**
     * Take the post-processed cURL data and break it down into useful header/body/info chunks. Uses the
     * data stored in the `curl_handle` and `response` properties unless replacement data is passed in via
     * parameters.
     *
     * @param resource $curl_handle (Optional) The reference to the already executed cURL request.
     * @param string $response (Optional) The actual response content itself that needs to be parsed.
     * @return BCS_ResponseCore A <BCS_ResponseCore> object containing a parsed HTTP response.
     */
    public function process_response($curl_handle = null, $response = null) {
        // Accept a custom one if it's passed.
        if ($curl_handle && $response) {
            $this->curl_handle = $curl_handle;
            $this->response = $response;
        }
        // As long as this came back as a valid resource...
        if (is_resource ( $this->curl_handle )) {
            // Determine what's what.
            $header_size = curl_getinfo ( $this->curl_handle, CURLINFO_HEADER_SIZE );
            $this->response_headers = substr ( $this->response, 0, $header_size );
            $this->response_body = substr ( $this->response, $header_size );
            $this->response_code = curl_getinfo ( $this->curl_handle, CURLINFO_HTTP_CODE );
            $this->response_info = curl_getinfo ( $this->curl_handle );
            // Parse out the headers
            $this->response_headers = explode ( "\r\n\r\n", trim ( $this->response_headers ) );
            $this->response_headers = array_pop ( $this->response_headers );
            $this->response_headers = explode ( "\r\n", $this->response_headers );
            array_shift ( $this->response_headers );
            // Loop through and split up the headers.
            $header_assoc = array ();
            foreach ( $this->response_headers as $header ) {
                $kv = explode ( ': ', $header );
                //$header_assoc [strtolower ( $kv [0] )] = $kv [1];
                $header_assoc [$kv [0]] = $kv [1];
            }
            // Reset the headers to the appropriate property.
            $this->response_headers = $header_assoc;
            $this->response_headers ['_info'] = $this->response_info;
            $this->response_headers ['_info'] ['method'] = $this->method;
            if ($curl_handle && $response) {
                $class='\Think\Upload\Driver\Bcs\\'. $this->response_class;
                return new  $class ( $this->response_headers, $this->response_body, $this->response_code, $this->curl_handle );
            }
        }
        // Return false
        return false;
    }

    /**
     * Sends the request, calling necessary utility functions to update built-in properties.
     *
     * @param boolean $parse (Optional) Whether to parse the response with BCS_ResponseCore or not.
     * @return string The resulting unparsed data from the request.
     */
    public function send_request($parse = false) {
        if (false === $this->isBaeEnv ()) {
            set_time_limit ( 0 );
        }
        $curl_handle = $this->prep_request ();
        $this->response = curl_exec ( $curl_handle );
        if ($this->response === false ||
                ($this->method === self::HTTP_GET &&
                  curl_errno($curl_handle) === CURLE_PARTIAL_FILE)) {
            throw new BCS_RequestCore_Exception ( 'cURL resource: ' . ( string ) $curl_handle . '; cURL error: ' . curl_error ( $curl_handle ) . ' (' . curl_errno ( $curl_handle ) . ')' );
        }
        $parsed_response = $this->process_response ( $curl_handle, $this->response );
        curl_close ( $curl_handle );
        if ($parse) {
            return $parsed_response;
        }
        return $this->response;
    }

    /**
     * Sends the request using <php:curl_multi_exec()>, enabling parallel requests. Uses the "rolling" method.
     *
     * @param array $handles (Required) An indexed array of cURL handles to process simultaneously.
     * @param array $opt (Optional) An associative array of parameters that can have the following keys: <ul>
     * <li><code>callback</code> - <code>string|array</code> - Optional - The string name of a function to pass the response data to. If this is a method, pass an array where the <code>[0]</code> index is the class and the <code>[1]</code> index is the method name.</li>
     * <li><code>limit</code> - <code>integer</code> - Optional - The number of simultaneous requests to make. This can be useful for scaling around slow server responses. Defaults to trusting cURLs judgement as to how many to use.</li></ul>
     * @return array Post-processed cURL responses.
     */
    public function send_multi_request($handles, $opt = null) {
        if (false === $this->isBaeEnv ()) {
            set_time_limit ( 0 );
        }
        // Skip everything if there are no handles to process.
        if (count ( $handles ) === 0)
            return array ();
        if (! $opt)
            $opt = array ();

        // Initialize any missing options
        $limit = isset ( $opt ['limit'] ) ? $opt ['limit'] : - 1;
        // Initialize
        $handle_list = $handles;
        $http = new $this->request_class ();
        $multi_handle = curl_multi_init ();
        $handles_post = array ();
        $added = count ( $handles );
        $last_handle = null;
        $count = 0;
        $i = 0;
        // Loop through the cURL handles and add as many as it set by the limit parameter.
        while ( $i < $added ) {
            if ($limit > 0 && $i >= $limit)
                break;
            curl_multi_add_handle ( $multi_handle, array_shift ( $handles ) );
            $i ++;
        }
        do {
            $active = false;
            // Start executing and wait for a response.
            while ( ($status = curl_multi_exec ( $multi_handle, $active )) === CURLM_CALL_MULTI_PERFORM ) {
                // Start looking for possible responses immediately when we have to add more handles
                if (count ( $handles ) > 0)
                    break;
            }
            // Figure out which requests finished.
            $to_process = array ();
            while ( $done = curl_multi_info_read ( $multi_handle ) ) {
                // Since curl_errno() isn't reliable for handles that were in multirequests, we check the 'result' of the info read, which contains the curl error number, (listed here http://curl.haxx.se/libcurl/c/libcurl-errors.html )
                if ($done ['result'] > 0) {
                    throw new BCS_RequestCore_Exception ( 'cURL resource: ' . ( string ) $done ['handle'] . '; cURL error: ' . curl_error ( $done ['handle'] ) . ' (' . $done ['result'] . ')' );
                } // Because curl_multi_info_read() might return more than one message about a request, we check to see if this request is already in our array of completed requests
elseif (! isset ( $to_process [( int ) $done ['handle']] )) {
                    $to_process [( int ) $done ['handle']] = $done;
                }
            }
            // Actually deal with the request
            foreach ( $to_process as $pkey => $done ) {
                $response = $http->process_response ( $done ['handle'], curl_multi_getcontent ( $done ['handle'] ) );
                $key = array_search ( $done ['handle'], $handle_list, true );
                $handles_post [$key] = $response;
                if (count ( $handles ) > 0) {
                    curl_multi_add_handle ( $multi_handle, array_shift ( $handles ) );
                }
                curl_multi_remove_handle ( $multi_handle, $done ['handle'] );
                curl_close ( $done ['handle'] );
            }
        } while ( $active || count ( $handles_post ) < $added );
        curl_multi_close ( $multi_handle );
        ksort ( $handles_post, SORT_NUMERIC );
        return $handles_post;
    }

    /*%******************************************************************************************%*/
    // RESPONSE METHODS
    /**
     * Get the HTTP response headers from the request.
     *
     * @param string $header (Optional) A specific header value to return. Defaults to all headers.
     * @return string|array All or selected header values.
     */
    public function get_response_header($header = null) {
        if ($header) {
            //            return $this->response_headers [strtolower ( $header )];
            return $this->response_headers [$header];
        }
        return $this->response_headers;
    }

    /**
     * Get the HTTP response body from the request.
     *
     * @return string The response body.
     */
    public function get_response_body() {
        return $this->response_body;
    }

    /**
     * Get the HTTP response code from the request.
     *
     * @return string The HTTP response code.
     */
    public function get_response_code() {
        return $this->response_code;
    }
}
/**
 * Container for all response-related methods.
 */
class BCS_ResponseCore {
    /**
     * Stores the HTTP header information.
     */
    public $header;
    /**
     * Stores the SimpleXML response.
     */
    public $body;
    /**
     * Stores the HTTP response code.
     */
    public $status;

    /**
     * Constructs a new instance of this class.
     *
     * @param array $header (Required) Associative array of HTTP headers (typically returned by <BCS_RequestCore::get_response_header()>).
     * @param string $body (Required) XML-formatted response from AWS.
     * @param integer $status (Optional) HTTP response status code from the request.
     * @return object Contains an <php:array> `header` property (HTTP headers as an associative array), a <php:SimpleXMLElement> or <php:string> `body` property, and an <php:integer> `status` code.
     */
    public function __construct($header, $body, $status = null) {
        $this->header = $header;
        $this->body = $body;
        $this->status = $status;
        return $this;
    }

    /**
     * Did we receive the status code we expected?
     *
     * @param integer|array $codes (Optional) The status code(s) to expect. Pass an <php:integer> for a single acceptable value, or an <php:array> of integers for multiple acceptable values.
     * @return boolean Whether we received the expected status code or not.
     */
    public function isOK($codes = array(200, 201, 204, 206)) {
        if (is_array ( $codes )) {
            return in_array ( $this->status, $codes );
        }
        return $this->status === $codes;
    }
}
/**
 * Default BCS_RequestCore Exception.
 */
class BCS_RequestCore_Exception extends \Exception {
}
